package main

import "fmt"

//0ms 100%,2.2MB 77%
func sumNums(n int) int {
	res := 0
	var sum func(int) bool
	sum = func(n int) bool {
		res += n
		return n > 1 && sum(n-1)
	}
	sum(n)
	return res
}

func main() {
	fmt.Println(sumNums(15))
}
